This invention relates to joints used in masonry construction and, more particularly, to a segmented movement joint used in a veneer/cavity wall system as well as other applications.
Wall systems having a masonry exterior are typically constructed of at least one vertical layer of masonry components and at least a second vertical layer of a material forming a back-up system. The back-up system may be constructed of lumber, light gauge steel studs or of a concrete masonry unit. The masonry and back-up systems are typically bonded together by horizontal metallic ties spaced apart vertically. A space is often provided in such wall systems (e.g., cavity wall systems) between the masonry and back-up systems for moisture drainage. The masonry wall or veneer includes numerous bricks or other masonry components arranged in various configurations to form the wall. Mortar is used between the masonry units and excess mortar is often difficult to control curing the construction of the masonry wall.
Because all materials in a building experience changes in volume, a system of movement joints is necessary to allow these movements to occur. The type, size and placement of movement joints is critical to the proper performance of the building. There are various types of movement joints in buildings including expansion joints, control joints, building expansion joints, and construction joints. Each type of movement joint is designed to perform a specific task.
An expansion joint is used to separate brick masonry into segments to prevent cracking due to changes in temperature, moisture expansion, elastic deformation due to loads, and creep. Expansion joints may be horizontal or vertical. The joints are formed of highly elastic materials placed in a continuous, unobstructed opening through the brick wythe. This allows the joints to close as a result of an increase in size of the brickwork. Expansion joints must be located so that the structural integrity of the brick masonry is not compromised.
A control joint is used in concrete or concrete masonry to create a plane of weakness which, used in conjunction with reinforcement or joint reinforcement, controls the location of cracks due to volume changes resulting from shrinkage and creep. A control joint is usually a vertical opening through the concrete masonry wythe. A control joint will open rather than close. Control joints must be located so that the structural integrity of the concrete masonry is not affected.
A building expansion (isolation) joint is used to separate a building into discrete sections so that stresses developed in one section will not affect the integrity of the entire structure. The isolation joint is a through-the-building joint. A construction joint (cold joint) is used primarily in concrete construction where construction work is interrupted. Construction joints are located where they will least impair the strength of the structure.
Although the primary purpose of expansion joints is to accommodate movement, the joint must also resist water penetration and air infiltration. Fiberboard and other similar materials are not suitable for this purpose because they are not highly compressible and, after being compressed, they will not expand to their original size. When placing expansion joints in brick, materials such as mortar or joint reinforcement should not bridge the expansion joint. If this occurs, movement will be restricted and the expansion joint will not perform as intended. Expansion joints should be formed as the wall is built. Sealants are used on the exterior side of the expansion joint to act as a seal against water and air penetration.
These are a few examples of movement joints utilized in the construction industry and this invention is not limited to any particular type of joint described herein or not described herein. Currently, many movement joints utilize a backer rod, which is a circular foam rod, behind the sealant to keep the sealant at a constant depth and provide a surface to tool the sealant against. The depth of the sealant should be consistent and generally one-half the width of the expansion joint, with a minimum sealant depth of ¼ in. (6 mm).
Problems often arise during the construction of a building or other structure, be it a cavity wall or other building system, in maintaining a proper spacing between adjacent building or construction components, such as the outer, masonry veneer and the inner wall. Commercial buildings have numerous lengthy joints between various components or surfaces. The joints must be sealed with caulking compound or other suitable material placed adjacent the surfaces of the components. Backer rods, typically produced from polyethylene, are initially installed in the joint at a specified depth with the remaining portion of the joint from the backer-rod to the outside surface then being filled with caulking compound.
The typical practice in installing a backer-rod is to initially force the backer-rod into the joint and to then further force the backer-rod to the predetermined depth by means of forcing a putty knife against the rod. Use of such a tool does not provide accurate depth control of the backer-rod since the putty knife does not provide any means for measuring the depth of the slot or joint once the rod is installed. Further, many commercial buildings have thousands and thousands of linear feet of joints requiring an inordinate amount of time for the installation of the backer-rod to the predetermined depth. If the joint is not properly constructed, the caulk may fail or separate from the adjacent components thereby jeopardizing the fluid impermeable joint when the components expand or contract in response to changes in the weather.
Municipal building codes differ from locale to locale and different construction techniques make predictable spacing for caulk application nearly impossible. Particularly, the spacing between the inner and outer walls is often different from building to building and even from location to location within the same building. As a result, the detailing and finishing work required for proper transition between building or construction components such as movement joints in a masonry veneer or cavity wall construction is typically very labor intensive, non-uniform and highly dependent upon the skill and experience of the particular contractor or tradesman performing the installation. Because of the importance and wide spread popularity of concrete and masonry structures, a better method for proper and consistent installation of movement joints between adjacent building components is needed.